Marine vessels

ABSTRACT

A marine vessel comprises at least one hull stabilized by at least one pair of outboard sponsons and propelled by propulsion means carried by the sponsons or hull. One aspect of the invention is shown in FIG. 7, where a marine vessel (20) is provided with first second pairs of outboard sponsons (230, 231), with the first pair (230) disposed forwardly of the second pair (231). The sponsons (230) of the first pair are disposed at a higher level than the sponsons (231) of the second pair. At the load water line (208) of the vessel, the sponsons (231) of the second pair are in contact with the water while the sponsons (230) of the first pair are disposed above the waterline (208). As shown in FIG. 12, should the vessel (201) heel to one side, the sponson (230) of the first pair on the heeling side of the vessel is brought into contact with the water, so as to create an upwardly acting restoring force (250) which tends to stabilize the vessel. Other aspects of the invention are disclosed.

BACKGROUND TO THE PRESENT INVENTION AND SUMMARY THEREOF

This invention relates to marine vessels.

EP-A-0 495 722 discloses a marine vessel comprising a central hullstabilised by first and second pairs of outboard sponsons and propelledby propulsion means carried by the sponsons or the hull, the first pairof sponsons being disposed forwardly of the second pair of sponsons, thesponsons of the first pair being disposed at a higher level than thesponsons of the second pair, so that, at zero heel angle, at the loadwater line of the vessel, the sponsons of the second pair are in contactwith the water while the sponsons of the first pair are disposed abovethe water.

The present invention relates to such a marine vessel, characterisedhowever in that, at zero heel angle, the waterline breadth of eachsponson of the second pair of sponsons is greater than the draftthereof, and that should the vessel heel to one side, the sponson of thesecond pair on the downgoing side of the vessel dips deeper into thewater, while the other sponson of the second pair which is on theupgoing side of the vessel emerges from contact with the water, and thesponson of the first pair on the downgoing side of the vessel issimultaneously brought into contact with the water, so as to stabilisethe vessel.

The hull may have a waterline length to beam ratio greater than 6 andpreferably 10.

The vessel may be provided with first and second pairs of outboardsponsons, with the first pair disposed forwardly of the second pair, thesponsons of the first pair being disposed at a higher level than thesponsons of the second pair so that, at the load water line of thevessel, the sponsons of the second pair are in contact with the waterwhile the sponsons of the first pair are disposed above the waterwhereby, should the vessel heel to one side, the sponson of the firstpair on the heeling side of the vessel is brought into contact with thewater, so as to create an upwardly acting restoring force which tends tostabilise the vessel.

The sponsons of each pair of first and second sponsons may be spacedfrom each other longitudinally of the vessel.

The sponsons of each pair of first and second sponsons may be combinedso as to form a single integral structure of stepped form.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The various aspects of the invention will now be described by way ofexample only with reference to the accompanying drawings, wherein:

FIG. 1 is a side view of a first form of marine vessel,

FIG. 2 is a plan view thereof,

FIG. 3 is a bow-end view which illustrates a modification,

FIG. 4 is a side view of a second form of marine vessel.

FIGS. 5 and 6 are plan views thereof,

FIG. 7 is a side view of a third form of marine vessel,

FIG. 8 is a plan view thereof,

FIGS. 9 to 14 are front views which illustrate the behaviour of thesponsons of the vessel at various heel angles, and

FIGS. 15 and 16 are side views which illustrate modifications.

In the figures, like reference numerals refer to like structures andfeatures.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, a marine vessel in the form of afreight ship 1 comprises a central hull 2 stabilised by a pair ofoutboard sponsons 3 flanking the stern end of the hull 2.

The hull 2 has a waterline length to beam ratio greater than 6. In thisexample, the ratio is 10. The waterline is shown at 8.

The sponsons 3 are pivotally attached to the stern end of the hull 2 bybridging structures 4 which are movable sternwards, relative to thehull, in a pantograph-like manner, so as to enable the hull to bemanoeuvred close to a quay or like structure for hull loading/unloadingoperations.

The pivot points for the sponsons 3 are shown at 10 and 11, whereby thesponsons fold about substantially vertical axes.

The hull 2 carries a bridge accommodation superstructure 5 and hasbulbous bow 6 and stern 7 structures.

The hull 2 defines four freight-carrying spaces in the form of cargoholds 9, with hatch covers 15, intended to accommodate cargo containers.

Alternatively, only a single freight carrying space may be provided ifthe marine vessel is to operate as a Roll-on Roll-off (RORO) ship.

The hull 2 is also formed with double-bottom tanks 16.

The sponsons 3 preferably have a waterline length of not more than 30%of the waterline length of the hull.

Details of the vessel 1 are as follows:

Overall length: 250 meters

Waterline length: 220 meters

Waterline width (of hull 2): 22 meters

Hull waterline length to beam ratio: 10

Waterline length of each sponson 3: 39 meters, i.e. 18% of hullwaterline length

Waterline beam of each sponson 3: 6 meters

Containerised cargo: 1000 cargo containers (each 6.096×2.438×2.438meters) Total length of cargo holds 9: 150 meters.

Propulsion and steering means for the vessel 1 are preferably carried bythe sponsons 3. The propulsion means so carried may comprise:

a) water-screw propellers, driving machinery therefor, and rudders,

b) steerable water jet units, driving machinery therefor,

c) water screw propellers, electric drive motors therefor, supplied withelectrical current by generators either disposed in the sponsons, oralternatively, in the hull 2, plus rudders.

Whatever form of vessel propulsion and steering means may be chosen, theobject should be to keep the stern of the hull 2 free of water-screwpropellers and rudders, and to avoid the employment of propulsionmachinery in the hull itself. Electrical generating equipment for dieselelectric propulsion may be carried by the hull 2, but this can bedisposed on the hull deck, leaving the hull free to accommodate freight.

The stern end of the hull 2 is also free to be shaped so as to have aform whereby resistance is substantially reduced, compared with aconventional vessel provided with a water-screw and a rudder.

Use of both bow and stern bulbous sections also reduces wave-makingresistance by creating wave-cancelling pressure fields at the bow andstern of the hull 2.

In the example illustrated, the bulbous bow 6 is larger and projectsfurther forward than on most conventional vessels, and is fairedupwardly and sternwards, back into the hull 2, as shown at 17. Thiscreates a fore-body which tends to run through waves rather thanresponding to them and causing the vessel to pitch.

The design also enables use of a stern bulbous section larger thanemployed conventionally.

Folding back of the sponsons 3 may cause the vessel 1 to becomeunstable. To avoid instability, water may be introduced into the doublebottom tanks 16, to serve as ballast. The water is subsequentlydischarged when the sponsons 3 are restored to their normal, ie extendedpositions.

With reference to FIG. 3, the vessel 1 may be provided with sponsons 3amovable about substantially horizontal axes 20 between inoperative(raised) and operative (lowered) positions.

With reference now to FIGS. 4 and 5, a marine vessel in the form of afreight ship 101 comprises a central hull 102 stabilised by two pairs ofoutboard sponsons 130, 131 flanking the stern-end midship portions ofthe hull 102.

The hull 102 has a waterline length to beam ratio greater than 6. Inthis example the ratio is 10. The length to beam ratio may besubstantially higher than 10 for a faster marine vessel.

The sponsons 130, 131 are attached to the hull 102 by fixed (ienon-folding) bridging structures 104 so as to enable the marine vessel101 to be manoeuvred fairly close to a quay or like structure for hullloading/unloading operations. (Container cranes generally have anoutreach of about 40 meters.)

If desirable, the bridging structures 104 may be made foldable.

The first and second pairs of sponsons 130, 131 of this example aredisposed one behind the other, as best seen in FIG. 5. The sponsons ofeach pair are disposed laterally of each other. The sponsons 131 of thesecond pair are aligned with the sponsons 130 of the first pair, andspaced longitudinally therefrom, whereby the wave trains 135 of thefirst pair of sponsons 130 beneficially interfere with the wave trains136 of the second pair of sponsons 131 so as to reduced wave resistance.

The longitudinal spacing S of the sponson pairs 130, 131 is such thatthe wave trains generated by the leading sponsons 130 are substantially180° out of phase with the wave trains 136 generated by the trailingsponsons 131. Thus the peaks of wave trains 135 interfere with thetroughs of wave trains 136 whereby wave-making resistance issubstantially reduced.

As a general rule, faster marine vessels would employ largerlongitudinal spacings of sponson pairs than slower ships.

Each fore and aft pair of longitudinally aligned sponsons 130, 131 arepositioned relative to the central hull 102 so as to allow beneficialinterference between the nett wave-making generated by the sponson andthe wave-making generated by the hull 102.

The sponsons 130, 131 need not be disposed in alignment in order toachieve wave train interference.

The hull 102 carries a bridge accommodation superstructure 105 and hasbulbous bow 106 and bulbous stern 107 structures.

The hull 102 defines freight-carrying spaces (not shown) in the form ofcargo holds intended to accommodate cargo containers.

Alternatively, only a single freight carrying space may be provided ifthe marine vessel is to operate as a Roll-on Roll-off (RORO) ship.

The hull 102 is also formed with the usual double-bottom tanks.

The sponsons 130, 131 preferably have a waterline length of not morethan 30% of the waterline length of the central hull 102. FIG. 6comprises a plan view at the waterline.

Details of the vessel 101 are as follows:

    ______________________________________                                        Overall length      250 meters                                                Waterline length    220 meters                                                Waterline width (of hull 102)                                                                              22 meters                                        Hull waterline length to beam ratio                                                                  39 meters, i.e. 18% of hull                                                                                      waterline                               length                                                    Waterline beam of each sponson                                                                            2.6 meters                                        130, 131                                                                      Waterline length of each sponson                                              130, 131                                          48 meters                   Containerised cargo                    1200 cargo containers (each                                                                      6.096 ×                           2.438 × 2.438 meters                                Total length of cargo holds 9                                                                              150 meters                                       ______________________________________                                    

Propulsion and steering means for the vessel 101 carried by the sponsons130, 131 may comprise propulsion and steering means as described above,with reference to the marine vessel 1 of FIGS. 1 and 2. However,propulsion engines are preferably located in the central hull 102 anddrive a contra-rotatable propeller 180.

In a modification of the marine vessel illustrated by FIGS. 4, 5 and 6the vessel may be converted to a catamaran type vessel. This isachieved, in effect, by removal of the central hull 102.

The shapes of the bulbous bows 6, 106 may vary according torequirements. For example, the bulbous bow 106 is non-faired, and thebottom of the bow extends upwardly and forwardly.

With reference now to FIGS. 7 to 14, a marine vessel in the form of afreight ship 201 comprises a single, central hull 202 (of waterlinelength to beam ratio grater than 6 and, as illustrated, about 10)stabilised by first and second pairs of outboard-disposed buoyantsponsons 230, 231.

The sponsons 230 of the first pair are disposed at a higher level thanthe sponsons 231 of the second pair so that, at the load water line 208of the vessel hull 202, the sponsons 231 of the second pair are inimmersed contact with the water level 252 (FIGS. 9 to 14) at water line208, while the sponsons 230 of the first pair are (normally) disposedabove the water 252 at waterline 208. As explained hereinafter withreference to FIGS. 9 to 14, should the vessel heel to one side, thesponson 230 of the first pair on the heeling or downgoing side of thevessel is brought into contact with the water 252 so as to create anupwardly-acting restoring force 250 which tends to stabilise the vessel201.

The marine vessel 201 is of substantially the same form and dimensionsof the marine vessel 101 of FIGS. 4 to 6 and thus requires littlefurther explanation, except in respect of the sponsons 230, 231.

However, the vessel 201 is provided with fore and aft ballast tanks 260,261 whereby the vessel is trimmed so as to ensure that the sponsons 230,231 are disposed where required, relative to the water line 208.

The sponsons 230, 231, which have a waterline length of not more than30% of the waterline length of the central hull 202, are spaced fromeach other longitudinally of the marine vessel 201 as indicated at S.The sponsons 230, 231 are also spaced outboard of the centrally-disposedhull 202, being connected thereto by bridging structure 204, which inthis example is non-foldable, but may be replaced by foldable structure.

The sponsons 230, 231 and non-foldable bridging structure 204, may becovered with decking 251 (FIG. 8) which may be extended in area beyondthat illustrated.

As in the case of FIG. 5, the sponsons 230 of the first pair of sponsonsare aligned with the sponsons 231 of the second pair thereof (FIG. 8refers).

FIGS. 9 to 14 illustrate what happens during progressive heeling of themarine vessel 201. FIGS. 9, 11 and 13 show the action of theaft-disposed sponsons 231 and FIGS. 10, 12 and 14 show the action of theforward-disposed sponsons 230.

It will be seen from these figures that at zero heel angle, thewaterline breadth of each rearward sponson 231 is greater than the draftthereof (FIG. 9 refers).

With reference first to FIGS. 9 and 10, these figures show the positionsof the forward and aft-disposed sponsons 230, 231 respectively, at zeroheel angle, that is with the hull 202 upright. In these positions, thebottoms of the relatively low sponsons 231 are immersed in the water252, thus providing the vessel 201 with initial stability, while thebottoms of the relatively high sponsons 230 are clear of the water 252.

FIGS. 11 and 12 show the marine vessel 201 disposed at a small angle ofheel. The aft-disposed sponson 231 (FIG. 11) on the heeling or downgoingside of the hull 202 now dips deeper into the water 252 while theaft-disposed sponson 231 on the upgoing side of the hull emerges fromcontact with the water. The forwardly-disposed sponson 230 (FIG. 12) onthat downgoing side is simultaneously brought into contact with thewater. This creates an upwardly-acting restoring force 250 on thedowngoing sponson 230, which tends to stabilise the vessel 201.

The restoring force 250 is assisted by a similar force 255 created asthe downgoing sponson 231 dips deeper into the water 252.

At a larger angle of heel, illustrated by FIGS. 13 and 14, the downgoingaft-disposed sponson 231 is immersed further into the water 252 whilethe upgoing sponson 231 of the pair is pulled clear of the water.

At the same time, the downgoing and upgoing forwardly-disposed sponsons230 are immersed deeper into the water 252 and drawn further away fromthe water 252 respectively.

FIG. 15 illustrates a modification wherein the first and second pairs ofsponsons 230, 231 are combined into a single integral or unitarystructure 256 of stepped form.

The step 257 is abrupt, in FIG. 15, but with reference to themodification illustrated by FIG. 16, a structure 256 may be profiled soas to have a rearwardly-sloping step 257a, whereby wave-impact forcesare reduced.

The forwardly-disposed sponsons 230 will also come into play should themarine vessel 201 be subjected to pitching forces.

Where possible, and where desirable, any of the above-described featuresmay be substituted for, or added to, each other.

Although mono-hull marine vessels have been described herein, thevarious aspects of the invention are not to be restricted thereto, asthey are also applicable to multi-hull marine vessels.

Similarly, although freight vessels have been described herein, thevarious aspects of the invention are also applicable to car ferries,with the following advantages compared with presently-known car ferries:

a) lower propulsive power

b) better vessel motion control

c) lower construction costs

d) wide deck area (decking 251 and extensions thereof)

e) possible use of heavier, more efficient engine machinery, due tolower weight sensitivity.

With reference to FIGS. 5 to 16 it will be noted that, in the case of atwo pair sponson arrangement, at least part of each forward sponson 130,230 is beneficially disposed in the stern half of the associated hull102, 202.

We claim:
 1. A marine vessel comprising a central hull stabilised byfirst and second pairs of outboard sponsons and propelled by propulsionmeans, first pair of sponsons being disposed forwardly of the secondpair of sponsons, the sponsons of the first pair being disposed at ahigher level than the sponsons of the second pair so that, at zero heelangle, at the load water line of the vessel, the sponsons of the secondpair are in contact with the water while the sponsons of the first pairare disposed above the water, whereby, at zero heel angle, the waterlinebreadth of each sponson of the second pair of sponsons is greater thanthe draft thereof, and that should the vessel heel to one side, thesponson of the second pair on the downgoing side of the vessel dipsdeeper into the water, while the other sponson of the second pair whichis on the upgoing side of the vessel emerges from contact with thewater, and the sponson of the first pair on the downgoing side of thevessel is simultaneously brought into contact with the water, so as tostabilise the vessel.
 2. A marine vessel as claimed in claim 1 whereinthe hull is for carrying payload.
 3. A marine vessel as claimed in claim2, wherein the hull has a waterline length to beam ratio greater than 6.4. A marine vessel as claimed in claim 3, wherein the hull defines atleast one freight carrying space.
 5. A marine vessel as claimed in claim1, wherein the sponsons of each pair of first and second sponsons arespaced from each other longitudinally (by distance S) of the vessel. 6.A marine vessel as claimed in claim 1, wherein the pairs of sponsons arecovered by deck structure.
 7. A marine vessel as claimed in claim 1,wherein the waterline length of each sponson (eg 3) is not more than 30%of the waterline length of the vessel hull.
 8. A marine vessel asclaimed in claim 1, wherein the sponsons of each pair are spacedlaterally from each other, the sponsons of the second pair being spacedlongitudinally (by distance S) from the sponsons of the first pair,whereby the wave trains of the first pair of sponsons interfere with thewave trains of the second pair of sponsons, so as to reduce waveresistance.
 9. A marine vessel as claimed in claim 8, wherein the peaksof the wave trains of the first pair of sponsons interfere with thetroughs of the wave trains of the second pair of sponsons.
 10. A marinevessel as claimed in claim 1, wherein one pair of sponsons is disposedat the stern end of the hull.
 11. A marine vessel as claimed in claim 1wherein the propulsion means are carried by the sponsons.
 12. A marinevessel as claimed in claim 1 wherein the propulsion means are carried bythe hull.
 13. A marine vessel comprising a central hull stabilized byfirst and second pairs of outboard sponsons and propelled by propulsionmeans, the first pair of sponsons being disposed forwardly of the secondpair of sponsons, wherein the sponsons of each pair of first and secondsponsons are combined so as to form a single integral structure ofstepped form, the sponsons of the first pair being disposed at a higherlevel than the sponsons of the second pair so that, at zero heel angle,at the load water line of the vessel, the sponsons of the second pairare in contact with the water while the sponsons of the first pair aredisposed above the water, wherein, at zero heel angle, the waterlinebreadth of each sponson of the second pair of sponsons is greater thanthe draft thereof, and wherein should the vessel heel to one side, thesponson of the second pair on the downgoing side of the vessel dipsdeeper into the water, while the other sponson of the second pair whichis on the upgoing side of the vessel emerges from contact with thewater, and the sponson of the first pair on the downgoing side of thevessel is simultaneously brought into contact with the water, so as tostabilize the vessel.
 14. A marine vessel as claimed in claim 13,wherein the step slopes rearwardly.
 15. A marine vessel comprising acentral hull for carrying a payload and stabilized by first and secondpairs of outboard sponsons and propelled by propulsion means, the firstpair of sponsons being disposed forwardly of the second pair ofsponsons, wherein the hull has a waterline length to beam ratio of atleast 10, the sponsons of the first pair are disposed at a higher levelthan the sponsons of the second pair so that, at zero heel angle, at theload water line of the vessel, the sponsons of the second pair are incontact with the water while the sponsons of the first pair are disposedabove the water, wherein, at zero heel angle, the waterline breadth ofeach sponson of the second pair of sponsons is greater than the draftthereof, and wherein should the vessel heel to one side, the sponson ofthe second pair on the downgoing side of the vessel dips deeper into thewater, while the other sponson of the second pair which is on theupgoing side of the vessel emerges from contact with the water, and thesponson of the first pair on the downgoing side of the vessel issimultaneously brought into contact with the water, so as to stabilizethe vessel.
 16. A marine vessel comprising a central hull stabilized byfirst and second pairs of outboard sponsons and propelled by propulsionmeans, the first pair of sponsons being disposed forwardly of the secondpair of sponsons, wherein the sponsons are moveable relative to thevessel hull, wherein the sponsons of the first pair are disposed at ahigher level than the sponsons of the second pair so that, at zero heelangle, at the load water line of the vessel, the sponsons of the secondpair are in contact with the water while the sponsons of the first pairare disposed above the water, wherein, at zero heel angle, the waterlinebreadth of each sponson of the second pair of sponsons is greater thanthe draft thereof, and wherein should the vessel heel to one side, thesponson of the second pair on the downgoing side of the vessel dipsdeeper into the water, while the other sponson of the second pair whichis on the upgoing side of the vessel emerges from contact with thewater, and the sponson of the first pair on the downgoing side of thevessel is simultaneously brought into contact with the water, so as tostabilize the vessel.
 17. A marine vessel comprising a central hullstabilized by first and second pairs of outboard sponsons and propelledby propulsion means, the first pair of sponsons being disposed forwardlyof the second pair of sponsons and the sponsons of the second pair beingaligned with the sponsons of the first pair, the sponsons of the firstpair being disposed at a higher level than the sponsons of the secondpair so that, at zero heel angle, at the load water line of the vessel,the sponsons of the second pair are in contact with the water while thesponsons of the first pair are disposed above the water, wherein, atzero heel angle, the waterline breadth of each sponson of the secondpair of sponsons is greater than the draft thereof, and wherein shouldthe vessel heel to one side, the sponson of the second pair on thedowngoing side of the vessel dips deeper into the water, while the othersponson of the second pair which is on the upgoing side of the vesselemerges from contact with the water, and the sponson of the first pairon the downgoing side of the vessel is simultaneously brought intocontact with the water, so as to stabilize the vessel.
 18. A marinevessel comprising a central hull stabilized by first and second pairs ofoutboard sponsons and propelled by propulsion means, the first pair ofsponsons being disposed forwardly of the second pair of sponsons, atleast part of each forward sponson being disposed in the stem half ofthe hull, the sponsons of the first pair being disposed at a higherlevel than the sponsons of the second pair so that, at zero heel angle,at the load water line of the vessel, the sponsons of the second pairare in contact with the water while the sponsons of the first pair aredisposed above the water, wherein, at zero heel angle, the waterlinebreadth of each sponson of the second pair of sponsons is greater thanthe draft thereof, and wherein should the vessel heel to one side, thesponson of the second pair on the downgoing side of the vessel dipsdeeper into the water, while the other sponson of the second pair whichis on the upgoing side of the vessel emerges from contact with thewater, and the sponson of the first pair on the downgoing side of thevessel is simultaneously brought into contact with the water, so as tostabilize the vessel.